It is really important to not to leave traces behind after the attack to successfully complete the job. The first step is to being anonymous while performing the attack, that is covering your face so it will be hard to trace back the attacker. In terms of computing, hiding your original IP is covering face. Whenever a computer opens a connection to another computer, the connection receiving computer would log the IP address of the connection initiating computer. These logs will be used in audit trails which helps investigators to locate the origin of an attack, most of the time it will be either your ISPs IP which will bring lots of troubles to your door. So you don't want the victim computer you are connecting to know your real IP, you need to fake/mask it so the victim will see the connection is originating from a different location of the world. This is done by creating the connecting through multiple intermediate computers. The victim will see the IP of the last